1. Field of the Invention
The present invention relates to a method and apparatus for detecting a shock-resistance performance of a head support member in a magnetic disk drive.
2. Description of the Related Art
Japanese patent publication No. 11-203637A discloses a contact detection device for detecting a contact between a head slider supported by a slider arm and a magnetic disk by sensing an acoustic wave produced on the slider arm due to the contact.
This known contact detection device can detect the contact between the magnetic disk surface and the head slider, but cannot detect a change in flying height of the head slider when the slider flies without contact. Thus, it is impossible to correctly detect a shock-resistance performance of a head support member such as a suspension when a shock or impact is applied to a magnetic disk drive.
In order to correctly detect the flying-height change, the inventors of this application have shot, by using a high-speed camera, movement of the suspension when a shock is applied thereto, and have obtained a change in flying height of the head slider or the suspension with respect to the magnetic disk surface from the shot image.
However, according to this conventional detection method using the high-speed camera, when the shock applied increases, the moving speed of the head slider and the suspension increases to decrease the resolution of each frame. Due to this decreasing in the resolution and the limitation of the shutter speed, spreading of light or blurring may occur in the image causing analysis of the image to make extremely difficult.
There is a method for detecting a change in flying height of the head slider without using a high-speed camera. According to this method, magnetic information signals previously recorded on a magnetic disk are read out by the magnetic head and the reproduced signal from the head is monitored when a shock is applied. Although this method can execute the detection even when a large shock is applied, correct detection of a change in flying height cannot be expected because the reproduced signal from the magnetic head varies depending upon the direction of the shock applied thereto.